Cementitious product.



C. ELLIS.

yCEMENTITIOUS PRODUCT.

APPLICATION FILED Nov. 9. IsII.

Ll. PIIIQIIIQII Aug. 24,1915.

Wwwwms.

LCA MM.

CARLETCN ELLIS, OF MONTCLAIR, NEW JERSEY, ASSIGNOR TO ELLIS-FOSTERCOMPANY, A CORPORATION OF NEW JERSEY. i

. CEMENTITIOUS PRODUCT.

T0 altre/0m it may concern Be it known that I, CAIiLE'roN ELLIS, acitizen of the United States, residing at Montclair, in the county ofEssex and- State of New Jersey, have invented new and usefulImprovements in Cementitious Products, of which the following is aspeciiication. l

The invention relates to cement clinker and cementitious products; andit comprises a product new in the art and also involving making ordinarycement clinker in a new, economical and advantageous manner; all as morefully hereinafter set forth and as claimed. v

In the most approved method of making clinker, the raw material intheform of a f fine dry powder is fed down and through a rotary inclinedkiln past a jet of iiame of opposed direction, and emerges at the lowerend in the form of granular, fritted or sintered aggregates, .of acomparatively large size, this size varying with the particularvmaterial treated and the operation of the particular kiln used, beingsometimes as large as two or three inches in diameter in the case ofeasy burning, or low time material, which is rather fusible: hardburning or high lime, material gives granules of rather less size. Inall cases in the ordinary Qperation, the product is delivered in thesevitreous, hard, clinkered or sintered lumps. i l,

It is one of the objects of the present invention kto control the sizeof; these clinker granules and also thedegree of sintering, since theformation of large hard-burnt lgranules increases the expense ofgrinding to form the nished cement.

Another' object isl to alternatively produce amaterial of equivalentcementitious properties which .will not be in hard clinkered lumps, butin a finer form, more cheanly,

and easily reduced to an impalpable pow The reactions in the formationof clinker as made in the usual way while many and diverse may be heregrouped lfor convenience into two mam classes; calclning and clinkering.In the iirst the raw material 4 loses the carbon dioxid of thecarbonates of lime, magnesia, etc., and also the water of hydration ofthe clay, the latter reaction occurring first in the point of time.During calcination in well regulated operation the organic 'mattersusually present in the Specification of Letters Patent. Patentd Auge 24g1915 Application med November 9, 1911.

Serial N0. 659,282.

clay are burnt out, sulfids oxidized to sulfates and ferrous compoundsconverted into ferrie. This last named reaction is very imhas something'of the same properties as alumina, viz., may Areplace part of the acidicconstituent, the silica. If therefore, the iron is not always oxidizedalike, the resultant cement is apt to vary in properties. One of thereasons for the free access of air in the ordinary operation of therotary is to secure these oxidations, and it is one of the objects ofthe present invention to secure this desirable uniformity of oxidationwithout access of unnecessary air which will result in the loss of heatand waste of fuel. Some 40 per cent. of the weight of the raw materialsare lostI in calcination, of which a percent. or two are due to a lossof water, burning of organic material, etc., some are due to dustinglosses, and the residue represents a loss of carbon dioXid. For the 380'the limestone are endothermic reactions, ab-

sorbing much heat, although not requiring a greatintensity or degree oftemperature. Like all endothermic reactions requiring the introductionof energy from without they are slow in speed and in this particularinstance they are further retarded by the pulverulent form of thematerial preventing a rapid transmission of heat through it; the more soas the material is giving olf relatively cool gases, -cool because of,the endothermic 'nature of the reaction, .and these tend vto retardactual contact of the hot gases of the kiln with the mass. It is forthis reason, among others, that the material is best 'treated in thin,agitated layers, and exposed to a long continued, soaking heat, in theendeavor to secure as far as possible a methodical progress of theseveral reac'- tions occurring; the dehydration, the roasting and thecalcining proper. Further, caleination being a reaction depending quiteas much upon the character and volume of the ambient gas mass as thesheer amount of heat supplied, to secure efficient calcination muchattention must be paid vto this lpoint,

the gas mass 'surrounding the calcining material being advantageouslylarge to dilute evolved carbon'dioXid as much as possible.-

For this reason also the treatment in thin agitated layers isbest.Liberation of carbon dioxid from calcium carbonate is a reactiondepending much upon the amount, or partial pressure of carbon dioXid inthe surrounding atmosphere. When this partial pressure is very high, ortotal, little or no carbon dioXid may escape and the carbonate maysimply fusedown or` remain unchanged at what would otherwise be a goodcalcining temperature. It is this phenomenon which is one of the causesof the vinefficient, calcination in the ordinary rotary where theevolved carbon dioxid, being much heavier vthan vair or hot flame gases,tends to iow xalong over the top of the calcines'retarding development.of more dioXid. With a suit able gas mass bathing the calcines,calcination may be efficiently performed at quite low temperatures. Insome degree, the temperature and the volume of indifferent gas bathingcalcining limestone are reciprocal factors.

, The conditions necessary for'the clinkering group of reactions, areradically dierent from those just described. Here there 1s llessnecessity for great amounts of heat .or a

large volume of gas, but the degree of temperature must ,be higher; highenough.-4 to cause the quicklime formed in calcination to enter intoreaction with the admiXed silicates to form the peculiar silicates andaluminates whose presence in cement gives it its settling properties. Itis necessary to furnish a temperature lwhich will finally 'cause theargillaceous silicates to enter into ent invention, it is however split'up into a plurality of stages. The reaction between the lime and the,cla-,f begins some time prior to the clinkerin'g into hard lumps and bycareful control of the conditions in the here-v inafter describedmanner, a union sufficient vto make al good cement may be effected priorto the actual clinkering or 'sintering into the ordinary y'hardclinkernodules or lumps. Thisuniting` reaction, which may be calledassociation, results inthe production of a finely granular material of amore or less i porous, unclinkered nature, which may be readily andcheaply ground to the impalpable powder necessary for cement and whichhas, in such condition, good setting powers. It' is usually of ayellowish. or brownish hue in lieu of the ordinary bluish hue of thefinished clinker. Whereordinary clinker is desired it is alsoladvantageous to go through the formation `of this preliminary orintermediate product since with all the associating reactions performed,when the material comes under the final heat radiating infiuence of theclinkering flame a y thorough uniform clinkering isquickly effected.

In the ordinary practical-both calcining and clinkering, despite theirdiffering character and requirements are performed in the v rotarykilns', the lheat for clinkering andthe hot gases for calcining beingfurnished by aflame of powdered coal and air injected intol theclinkerin'g end of the kiln. In its standardized form,-the rotary isabout 60 to .100'

feet long, rarely more; is inthe neighborhood of 5 ft. internaldiameter, and iis provided with a short broad stack, seldom more.

than 60 to 80 feet high. None of these dimensions are arbitrarilychosen; each is inter-dependent on the other and on the ordinaryaccepted methods of operating the kiln. They are, as a matter of fact,compromises between conflicting requirements -among which thermal andchemical conditions have I l been little considered, save in the matterof v furnishing a sufficiently high temperature in the cli'nkering zoneof the kiln. The diameter, for instance, is a compromise between outputand coal consumption, extensive experience having shown that increasesin diameter require much more fuel per barrel of cement. And with vthewidth is correlated the length. There are al number of co-y operatingreasons for this correlation between width and length, and thelimitation `of both in the ordinary practice. One is that since the hotgases tend to rise in the arch of the kiln in the calcining zone, thistendency being reinforced bythe presence of an uriderflowing current ofcooler air and carbon dioXid, five feet in the calcining zone representabout the greatest practicable distance through which these gases Willimpart useful amounts of heat to the calcining material beneath. And bythe time the gases lhavetraveled 60 ft. longitudinally of the kiln,though still ata temperature well in h ot enough to do further workunder `these circumstances,- and are discharged. Itis obvlous that underthese circumstances eXtra 'excessl of 1500 degrees F., they are yet notlength 'isnot worth its expense. Besides,

such eXtra length disturbs the carefully adjusted draft relations ofthecoal fiame in the.

.While some heat is im-BO clinkering zone. parted by the hot gases tothe arc of thekiln which upon rotation becomes the bottom in its turn,this has no very important heating efl'ect upon the calcining material,the rei` fractory kiln lining not being well adapted to impart heat bycombustion, norA the powder to receive it. The resultant heat lossesare, as is well recognized in the art, inordinate. Over 100 pounds ofcoal are used per barrel of finished cement, (380 lbs.) in lieu of theless than 25 lbs. indicated by thermochemical data. The convenience andeconomy otherwise of the rotary kiln have lead it to supersede olderprocesses handling slurry and operating discontinuously, but the wasteof fuel it involves, as stated, is well known. Coal costs less thanlabor and the rotary kiln gives a large output with a minimum of labor.In the clinkering zone of the kiln the conditions usually maintainedrepresent still further compromises. There are few cheap fuels capableof yielding the high temperature here required; viz., one high enough tocause the incipient fusion or sintering of the silicates, etc., whichwill enable their reaction with the quicklime. Of these the mosteligible has been so fai' a burning jet of powdered coal carried insuspension in an aircurrent, and it is the one which has hitherto beengenerally used. Unfortunately, the temperature required to frit clay isbut little below that at which kiln 'linings are damaged or below thatat which clinker fuses and the coal flame over` Consequently it hasflame axially of the kiln, permitting no direct impingement, andtempering the heat somewhat by a sheath of air surrounding the flame andshielding kiln walls and clinker therefrom. Here again the conventionalfive feet diameter becomes an important factor, for the cross-sectionalarea of the flame increases at a greater rate than its most importantpart, its radiating circumference, and with greater diameters, theamount of coal required to produce a sufficient fiame rapidly increases.To furnish this heat-tempering sheath of air, an unnecessary excess isvoften allowed to enter into the kiln representing another waste of fuel.*Furthermore the usual kilns and method are only adapted to handle rawmaterials; preferably those of minimum bulk. The calcining zone is notable to handle as much material as the clinkering zone, since, asstated, calcination is comparatively slow and clinkering iscomparatively quick, and since the material must be in thin layers.Marl-clay mixtures take up too much room in the cal cining zone, and theordinary kiln simply cannot deal with enough material in such mixturesto give the normal output. For this reason a number of plants built totreat marl have had to abandon it and substitute limestonegin some caseshauling the latter material long distances with large supplies of marlavailable. In certain of these trials, the same amount of coal with thesame number of cubic feet of raw material produced twice as much clinkerwith the limestoneclay mixture as with the marl mixture; or, to state itin another way, the marl mixture required twice as much coal and twiceas much labor, time, etc., as the other.

` From the foregoing, it will be obvious why the ordinary kiln, thoughordinarily regarded as a fairly good clinkerer is a most insufficientcalciner and why it is wasteful of fuel. The clinkering sectionrepresents too great a fraction of its length and the hot gases are notwell utilized in the short calcining zone. Calcination is areactionrequiring a comparatively long time; it re- 'quires a high timecontact factor.{*And,

even were they better utilized, the ltime given the material in itspassage through the calcining zone would still be altogether too short.vIn a 60 foot kiln the clinkering zone occupies perhaps 20 ft. or aboutone-third,

only 40 ft. or less being devoted to calcining. This gives the materialfar too little time for calcining. Longer kilns run under the usualconditions do not give more, for reasons stated. The result is that thematerial enters. the clinkering zone only partially calcined,complicating the clinkering action by the necessity of direct expulsionof carbon dioxid by silica, etc., a reaction absorbing much heat andproducing a sudden chilling at this point which tends toward ringformation in the earlier stages of clinkering, and irregularity ofproduct. Agglomerated bodies of the material are apt to form with anexterior sintered shell, causing what is called a nigger-head andthrough this shell the heat penetrates imperfectly, the

material not being conductive and the endolthermic calcining reactionwithin opposing heating. This is a frequent source of under-burning. Ifthe clinkering heat be forced to convert these masses, the clinker is-very apt to be locally overburnt.

the present invention. F or this purpose, I

have rearranged the conditions of operation, departing altogether fromconventional dimensions and conditions with the result of securing abetter and a much more even and economical operation. In lieu of passinga quick draft of intenselyhot gases above all isa

the calcining material in the e'ortto make-` lformed .by preventing theusual stratification of the gas currents. `My flame gases, as a matterof fact, I preferably hold in contact with the material vfor a length oftime sufficient to insurethat their temperature shall be reduced to theminimum necessary for securing natural draft, or, say- 400 degrees F.,thereby saving the enormous waste of heat of the usual methods. Andsince these gentle movements of gases do not tend yto pick up dust asdoes the inordi- -nate velocities obtained under the usual practices, Iam enabled to use the. ordinary chimney stacks in lieu of thespeclallzed, dustcollecting, short, wide stacks of the prior art,

or I vmay even use mechanical draft means,

in case still lower temperatures in the waste gas are desired, utilizingthe h'eat in drlers,

' or elsewhere. yBy removing the gases at these low temperatures noregenerators are necessary, the kiln being its own heat saver, thoughthey may of course be used if desired, the gases often being practicallydustless. If clinkering is carried to the vitrifying stage, a quickdraft is as necessary as before in the clinkering zone, both to secureintense combustion and great heat andl to support the relatively greatermass of the burning coal, but here also by certain expedients I am ableto economize on the amount of air which must be introduced and thereforeheated, thereby saving fuel. In making the product of the presentinvention I preferably also dispense with the conven tional air sheatharound the ame so far as possible. vIf a completely sintered andVitrifled product is desired, I arrange the conditions to produce aspecial clinkering zone of the usual length, or perhaps four or fivefeet longer, say *25 feet, maintaining it in a zone beginning somewhatback of the mouth `of the kiln. In lieu of directing the flame axially,1I may impinge directly, lessening the amount of coal which must beusedto produce the temperature and I aim to obviate local overheating bya more rapid rotation'of the kiln. This rapid rotation, which may be inexcess of one revolution per min-v ute, carries the clinker up on theside of the kiln, and I can therefore impinge by a sidewise direction ofthe flame. j

I'prefe'r to restrict the amount of air gomuch ing into the kiln toapproximately that necessary for combustion, using a hood at theclinkering or lower end and allowing in the air supplied to the jet forthe amount necessarily entering through sight holes, patching holes,etc., thereby saving fuel andlalso preventing stratification to someextent.

In the usual. operationr of the; ordinary kiln there is a violent rushof hot flame gases along the crown of the kiln and a concomitant iniowof colder air beneath these gases and over the materials being treated,through which air the heat must be transmitted. v As calcining yisendothermic, this y difference in temperature andthis stratificationtend to be preserved throughout the length of the kiln. And I controlthe con! ditions so that intermediate the clinkering and calciningvZone. I establish and mai`n. tain an associating' Aor s combining zonewherein the calcined material undergoes transformation into pulverulentincipient material under prolonged exposure to the penetrating heat andsurface action 'of the light of the incandescent flame gases from theclinkering zone proper. Since powders as such ordinarily react veryslowly for the present results, vthe associating zone must represent acomparatively large fraction of the total kiln length. And it must besupplied with material substantially completely v lcalcined -In thepresent invention means are accordingly provided tol bring aboutvt'o avery substantial extent reactions which have been heretofore beenlookedupon as impossible of `attainment except in the enor- -mously hightemperature of the'clinkering zone while the material was undergoingpartial fusion.

Contrary to the prevalent belief, is posl sible by the properapplication of heat (and light under high temperature conditions) and bysecuring the proper time element or time contact of the heat, (andlight) to accomplish in a large degree in the associating zone thereactions ordinarily taking place in the clinkering zone, and too,without the disadvan# tage of seriously hardening the material bypartial fusion or vitrification. This afo'rds. the marked advantage thatthe'operation of the clinkering zone proper is rendered much more rapidand efiicient and proceeds at a relativelylower temperature. 0r what isthe same thing, with a flame f a Certain ltemperature, in the clinkeringone proper, more, associated material will be clinkered than ordinaryealcines. Thereby a greater output with attendant reduction in fu'elcost is secured. Furthermore, by conducting certain of the reactionsordinarily carried out in the clinkeringzone under vitrifying, (ratherthan true clinkering) conditions, the finished clinker may be turned outin a much more `porous or even friable condition than where clinkeringhas to be iat carried to the extreme to produce sound cement. rlhus onegreat element of cost, that of grinding the vitriedmaterial, or clinkerto make cement, may be materially reduced. Also the clinker may beground to a greater degree of fineness than is customary withoutexcessive cost. As only the finer portions of cement are instrumental inconferring cementitious properties to the product, it will be evidentthat the present invention tends to reduce the great waste of materialthrough the presence in ordinary cement of coarse particles possessinglittle or no cementitious properties.

It will be seen that in the zone beyond the clinkering Zone heretoforeemployed substantially solely for the purpose of imperfect calcination Iestablish wholly new conditions. I lengthen the rela-tive time ofcontact of the hot gases with the material in the so called calciningzone, as compared with the time of contact with the material in theclinkering zone at least sevenfold; or, which is much the Asame thing, Ilengthen the period of travel of the material therethrough Sevenfold as,compared with the time of travel through the clinkering zone. This isnecessary to secure complete calcination and present the material to theclinkering zone free from carbon dioxid, uniformly heated throughout itsmass, and in a high state of association ready for the final transitionin the clinkering zone. Vhile in the ordinary kiln of a length of ft. orso, or even in kilns of 150 or 125 ft. in length the clinkering flamehas to do much of the calcining to the detriment of the operations inthe clinkering zone, in the present invention the operation `ofcalcination is conducted as a substantially separate step underconditions which permit of an intermediate zone wherein association canprogress. Hereinafter the term decarbonating` zone will be used todesignate that portion `of the path of travel of material in .which "thecalcining predominates and substantially progresses or completes itself,while that portion of thepath wherein association without vitrificationsubstantially occurs is designated as the associating zone. Thus theseven fold eX- posure area or path of travel beyond the clinkering zoneis resolved into two zones, that essentially for decarbonating and thatessentially for associating. I In this sevenfold portion the bestarrangement is a twofold association zone and a five-fold decarbonatingzone, so that the ratio of effective clinkering, associating anddecarbonating areas or zones becomes as l :2 :5 depending on thematerial to be treated, whether lcement rock, marl and clay, slagandolimestone, etc., these relations may be modified somewhat to securethe best adaptation. vIn order to heighten this time-contact factorbetween raw material and hot gases, however, I also preferably retardthe velocity of lthe latter so that my time contact is really greaterthan Sevenfold. For the sake of convenience however, I shall hereinafteruse the word Sevenfold as applied to the total length of associating anddecarbonating zones, it being understood that this term actually refersto the time oftravel of the solid material rather than thetrue time-Contact factor between gases and material, which is much greater andmuch more important. Using the stated length of clinkering Zone, or thespace in which the material is exposed to heat radiation from anactively burning Vitrifying flame of 25 ft. or thereabout, I make thespace between such heat radiating influences of this special character',.embracing both the associatingv and decarbonating Zones, or the path oftravel of the material. therethrough, seven times as long, or longer, orthe equivalent of 175 ft. or more. And for the best results the lengthofthe associating zone becomes` about 50 ft., and that of thedecarbonating zone about 125 ft. or more. In the ap aratus hereinafterdescribed, such zones may be maintained under predetermined conditionsof Haine application, etc., by the use of a novel type of rotary kilncharacterized by its enormous length ranging from 200 ft. to 350 ft. ormore from end to end, preferably however of a length of about 250 ft. Insuch an apparatus perhaps ten feet, more or less at the lower end, orfatthe mouth ofthe kiln` are used for igniting the fuel and as a heatregenerator due to the passage of the incoming air or fuel over theincandescent finished clinker. Beyond this, for a space of 25 ft. or so,is the clinkering zone proper,

then follows a space of 50 ft. or more deft. or so, and the remainder ofthe kiln is i taken up by thedehydra-ting operation, and the heating upof the cold raw material preparatory to entry into the decarbonatingzone. It is also of course necessary to secure contact of the hot gaseswith the material. With the simple long kiln, if some care be taken toavoid stratification of gases at the clinkering zone, and accessof airat points throughout its length, this actual contact may be readilysecured and also the desired retardation of velocity of flow. Assumingthe kiln to be of the same diameter throughout and the gases of atemperature of about 3,000 F. in the clinkering. zone and 400 F. at theoutlet their volume contracts to be about a fifth, 100 cubic feetbecoming about 20. As the cross-'sectional area of the kiln is assumedto be the same, this means a corresponding diminution of theirtranslational velocity. I however, preferably increase the diameterofthe kiln in the associating and decarbonating zones, slowing down thevelocity still more. In the chimney stack, the cross section of the fluecan be made appropriate to the new volume to give good draft and thedraft in the mouth of the kiln maintained. i In other words, I take themoving body of gases throughout such an apparatus, maintaining it inquick motion in the clinkering zone and chimney stack and may slow downits motion in the intermediateassociating or decarbona'ting Zones. Thisslow motion has a-'number of concomitant advanwith the same length ofkiln, permits diftages; it prolongs the time .contact factor fusion ofevolved carbon dioxid into the gas mass and prevents stratification',the Irevolution of the kiln tending to circulate the slow moving gases,in a way not possible with the rapid draft current in the upper part ofthe kiln inthe common operation.

In using a kiln of the character described, it can be made in sectionsto gain structural strength and rigidity, the sections beingtelescopically connected or connected by stationary'housings, the llatter being preferable as permitting more freedom in the matter ofdiameter. Such a sectional kiln can be made in two or three sections ifdesired, andl each provided with its own drive means permittingdifferential drive. I prefer to rotate the lower or clinkering end ofthe kiln rather rapidly to carry the clinker upward on the side, and theupper or decarbonating end rather slowly to increase the time contactfactor, inclining the said clinkering section rather less to compensatein the matter of speed of transit therethrough for the increasedrapidity of rotation. In this clinkering section the rotation should notbe less than one revolution per minute and the inclination may beone-half an inch per foot, while the calcining section may runthreequarters of a revolution and have an inclination of, say,three-quarters inch. a

F or reasons already stated in regard lto gas velocity and for thepurpose of securing larger capacity in the decarbonating zone, I preferto make the latter larger in diameter., than either the associatingorthe clinkering zones. For example in a three section inclined kiln theupper section employed for decarbonating may be 30 ft. in diameter, theintermediate or associating section 20 ft. in diameter, andthe specialclinkering section 12ft. in diameter. I thereby secure ability to treatthe voluminous marl mixtures with a normal output, since in calcinationshrinkage occurs. AWith kilns of uniform diameter andwith the usualmaterials, the capacity of the clinkering zone to handle material isgreater than that of the calcining and it is well therefore to enlargethe diameter here. This also 'has the result of forming a sort ofdominant pool7 of material.' But in no case should the structure of thedccarbonatrial, or mix.

ing section or the rate of feedvbe such as to accumulate materials inVery heavy, thick layers, since these do not calcine well for statedreasons, unless somlespecial means be adopted to secure gas contact andheat distribution throughout the mass.

` In the accompanying diagrammatic draw- :bonating zones, or simplyassociating and decarbonating zones according to the product required.For high association efficiency the diameter of the kiln is not whollyan unimportant consideration, and a kiln of this length may haveadiameter of about l5 ft.

in order to afford the proper spread and exposure of the associatingmaterial to radiate heat and light; the latter having a probablyimportant, though obscure action in associa-v tion. A kiln having adiameter of about 30 ft. is better from the point of effectiveassociation but difficulties arise in connection with anchoring thelining firmly in a kiln of thisdiarneter, hence the abovestated diameterof fifteen ft. On the other hand, the diameter must notbe restrictedgreatly to secure the special products of the present invention. Adiameter of six or eight feet for example tends to reduce association toan undesirable minimum and kilns at least l2 ft. in diameter should bestbe employed to secure the benefits of the substantial institution ofassociating reactions. l

The drawing shows a singleinclined rotary kiln of enormous length-QOOft. to 350 ft. -and preferably approximately 250 ft., having a diameterof from 12 to 20 ft., and

preferably about 15 ft. The kiln 1, is pro- 105 vided with a housing 5,at its upper end, and a stack, 6, for the withdrawal of the spentproducts of combustion. The conveyer 7, serves to introduce the rawmateis inclosed by the hood, 8, and as shown is fitted with the powderedfuel blast pipe 9. Raw material'is entered into the upper part of thekiln and the powdered fuel jet at the At the lower end, the kiln lowerend is ignited. With proper fuel and maintenance of proper conditions ofcombustion, because of the enormous length of the kiln the removal? ofthe carbon dioxid is substantially completed long before the ma- Vterial enters the clinkering zone, while between the calcining and theclinkering zones proper may be produced the described associating zone.The material, with its greatly reduced content of carbon dioxid entersthe associating zone where, dry clinkering progresses and with a lengthof. zone which lof reactions which in theI ordinarykiln would be forcedto take place in the clinkering zone. The dry clinkered material atymakes possible the institution or completion length enters theclinkering zone and there the final reaction of clinkering progresseswith remarkable smoothness and thoroughness. Or, if the clinkeringoperation is to be 'dispensed with the heating flame is regulated so lasto discharge from the kiln a partially fritted mass of associated orcombined cement materials, which mass consists of relatively smallporous granules possessed of cementitious properties and on furtherheating being adapted to coalesce into ordinary cement clinker Withoutsubstantial change of composition.

In prior applications, Serial Nos. 316,148 and 578,664, filed May 10,1906'and Aug. 24th, 1910, I haveA described and claimed a process andapparatus for making cement in kilns of enormous length. Such apparatushas been recommended hereinefor the purposes hereof and withoutlimitation thereby, v

\ are in .substantially true combination approximately similar towell-clinkered Portland cement; such cement material being substantiallyfree of carbon, dioxid and consisting of, or comprising, relatively softor porous granules possessed of cementitious -properties and saidgranules upon further heating being adapted to coalesce into cementclinker approximating ordinary `vitrified clinker and Without anymaterial or substantial change of composition.

W'hat I claim is As a new article of manufacture a partially frittedmass of associated cement materials in substantiallythe proportions ofPortland cement, the components of which are in substantially truecombination approximately similar to Well clinkered Portland cement;said mass being substantially `free of carbon dioxid and consisting ofrelatively soft porousgranules possessed of cementitious properties andsaid granules ony further heating being adapted to coalesce into cementclinker ofg-ordinary vitried character and Without substantial change ofcomposition.

In testimony whereof I afiix my signature in the presence of witnesses.

. CAR-LETON ELLIS. Witnesses:

WALTER BLADEN, NATHANIEL L. FOSTER.

